1. Field of the Invention
The present invention generally relates to relief of pain in animals using radio frequency electrical signals and, more particularly, to a method and apparatus for equine pain therapy using RF stimulation and lesioning techniques.
2. Description of the Prior Art
The management of pain in animals, particularly large animals such as horses, of the family equinadae, has traditionally relied on rehabilitation strategies, pharmacological intervention and the like. Though often effective, such therapies require significant amounts of time during which to recover from the injury or illness that caused the pain. Further, progress in such therapies may be limited by the presence of the pain during exercises or by the affects of the drugs administered to alleviate the pain while attempting to resume normal function. Moreover, for animals such as horses, that participate in competitive events, drug therapies are often impractical because of rules for drug testing that preclude the use of drugs in the management of pain. Another disadvantage of drug therapies is that the effects are short-lived, lasting only as long as the drug is administered. Further, prolonged reliance on drugs can result in an accumulating resistance to the affects of the particular drug and/or a dependency or difficulties in weaning the patient of continued treatment with the particular drug. Thus, there is a need to provide effective long-term management of chronic pain in animals with minimal significant pharmacological intervention.
The use of pulsed radio frequency (PRF) stimulation—i.e., neuromodulation of peripheral nerves—for medical purposes is not new. In humans, PRF has been described as a therapy for transiently deactivating ADC peripheral nerve fibers. The ADC peripheral nerve fibers are exclusively responsible for chronic pain, while leaving nerve fibers for neuromuscular, acute pain, proprioception (sensory reception of stimuli in muscles, tendons and joints), etc. intact. In general, after the site on the patient's skin is located, aseptically cleansed and desensitized, the peripheral nerve is accessed percutaneously, i.e., through the skin, via a small incision in the skin. The PRF probe is introduced through the incision and applied directly onto the selected peripheral nerve. The PRF energy is regulated as to amplitude, pulse repetition rate and time duration. Also monitored are the impedance of the probe/patient connections and the temperature of the tissues at the probe tips.
However, the use of PRF for pain management in veterinary medicine has not been described heretofore. Several problems must be overcome. One is, while the peripheral nervous systems of animals in principal is very similar to that of humans, the anatomy of animals differs significantly and requires the development of techniques adapted to these anatomical differences. Further, the RF energy parameters that are effective for the treatment of chronic pain in animals are not necessarily the same as used in human PRF therapies. Another is that animals are generally covered with hair, which requires shaving, removal of the natural oils on the skin and antiseptically preparing the skin. This is typically a cumbersome procedure and leaves a bare, unsightly patch of skin until the hair grows back to its previous condition. Moreover, the PRF probes currently available are not well-suited for use with most animals because of size variations and the need for providing a reliable electrical connection to the nerve tissue of animals. Thus, there is a need for PRF apparatus and methods adapted for use in treating chronic pain in animals, as described herein below.